1. Field of the Invention
The disclosed apparatus pertains to the art of motorized passenger loading bridges and particularly to the apparatus used to control the alignment of these passenger loading bridges to the doors of the vehicle or vessel with which the passenger loading bridge is mating. The disclosed apparatus in particular refers to the control system for computer-aided/manual, tele-robotic, and automatic operations. Passenger loading bridges include, but are not limited to, airbridges and ship's covered gangplanks.
2. Description of the Prior Art
Passenger loading bridges are used to convey people between vehicles such as airplanes and ships and buildings such as airport or ship terminals. They are well described in U.S. Pat. Nos. such as Nos.: 2,700,164, 2,875,457, 3,038,185, 3,046,908, 3,060,471, 3,310,823, 3,315,291, 3,404,417, 3,683,440, 3,913,757, and 4,852,197 among others. Airbridges are used at most airports.
The operator consoles used on existing passenger loading bridges vary greatly from each other. Each manufacture has one or more console layouts for each airline and each model or variation of their passenger loading bridge. The actual operation of current passenger loading bridges has been inefficient resulting in costs to the airlines from docking delays and accidents. Also, training costs have been too high because of the variety and complexity in operator consoles and high staff turnover. Passenger loading bridges as typified by airbridges are currently operated by personnel of varying training and experience. This results in potential danger to both the airplane and airbridge. This is compounded by the situation wherein the sensors and displays currently used in airbridges are inherently unacceptably unreliable.
"Tele-robotics" refers to the engineering field of remote control with emphasis on the operator feeling as if they are in the location of the equipment being controlled via feedback such as video cameras and sensors, and being able to project their "presence" and control to that location. This has particular impact in that the operator can perform the same function whether using a control console actually located at the end of a passenger loading bridge or at any arbitrary distance away. Tele-robotics is actually a hybrid of "unadulterated" remote control and full automation. Specifically, the operator operates the system as if it were in manual, i.e. hardwired, but instead the computer interprets the commands and then modifies them greatly, slightly, or not at all based upon sensor data, the situation, and control algorithms.
Control systems for passenger loading bridges have been patented both by themselves, and more often, in the case of some of the simpler systems, within a general passenger loading bridge patent. These patents include U.S. Pat. Nos.: 2,688,761, 3,03,185, 3,046,908, 3,060,471, 3,310,823, 3,317,942, 3,369,264, 3,538,528, 3,543,318, 3,561,030, 3,599,262, 3,665,536, 3,683,440, 3,808,626, 3,827,590, 3,913,757, 4,333,194, 4,318,197, 4,318,198, 4,344,200, and 4,860,975. Most of these patents only cover simple wiring. The relevant patents are discussed in detail:
U.S. Pat. No. 4,318,197 "Conveyance Loader Drive and Steering System". From an engineering standpoint, this is a good mechanism with a poor user interface. It does not account for the fact that the user located in a rotatable vestibule, and as such, is orientated at a random position relative to the cabin and hence wheel carriage below the cabin. This is a situation which occurs most of the time with most of the passenger loading bridges. This patent mentions most practical variations except computer. It does not have sensors for measuring rotation of the wheel carriage.
U.S. Pat. No. 3,683,440, "Automatic Terminal Bridge Control System", mentions people and vehicles on the ground whose safety must be insured, however, it does nothing to facilitate this. To remedy this, the newly disclosed apparatus provides a camera and optional sensors to watch the area around the wheel carriage. Unlike the system shown in U.S. Pat. No. 3,683,440, which requires reflective tape, the newly disclosed apparatus shows in the fully automatic mode how the system can also automate the process but will not require any modification to the target vehicle. Airlines, for example, do not like to put on reflective tape, bar code, or other alignment/ranging markings on their airplanes. Prior art shows that inventors like to use such markings. This non-obvious approach satisfies the user's requirements without the shortfalls of previous inventions.
U.S. Pat. No. 3,913,757, "Control System for Load Carrier and Associated Transfer Apparatus", covers maintaining the axes of the freight (un)loading bridge relative to an airplane. It does not cover how the bridge was brought into position which is what the newly disclosed patent covers.
U.S. Pat. No. 4,860,975, "Smart Tunnel-- Docking Mechanism", is overly smart. It uses a computer where a human operator would be more efficient. The result is a system which requires too much instrumentation, has too little flexibility, is very susceptible to failure, and undoubtedly will be very expensive to implement.
U.S. Pat. No. 4,318,198, "Conveyance Loader Wheel Position Indicator", appears to show wheel angle relative to tunnel rather than relative to the operator. Thus the joystick does not necessarily command the air bridge to move in the desired direction due to the frame of reference and the interaction between the wheel carriage motion and the length of the tunnel pinned at the terminal.
Most indicators in current use in airbridges are analog displays which are inherently unreliable due to voltage and calibration drift. Also an analog sensor is unsuitable for use with passenger loading bridges which have wheel carriages having a range of motion approaching or exceeding 360.degree.. This is because, of the discontinuity between 360.degree. and zero.
U.S. Pat. No. 4,942,538, "Telerobotic Tracker", is a classic telerobotic implementation. It differs from ours in the two critical areas that we are trying to patent: how our system displays, and how our system controls the passenger loading bridge. Yuan's system is concerned only with how to cancel out relative motion of a known target relative to the telerobot. Our system works for any target, and assumes a motionless target. Yuan's system requires a frame grabber while ours does not.